Which of the following would attempt to compensate for the decreased cardiac output with congestive heart failure?
slow cardiac contractions
increased renin and aldosterone secretions
decreased erythropoietin
decreased catecholamines
The Correct Answer is B
A. Slow cardiac contractions: Slowing the heart rate would reduce cardiac output further in congestive heart failure, worsening tissue perfusion. Compensatory mechanisms aim to maintain or increase cardiac output, so slower contractions are not part of the adaptive response.
B. Increased renin and aldosterone secretions: Decreased cardiac output triggers activation of the renin-angiotensin-aldosterone system (RAAS). Renin release leads to angiotensin II formation, causing vasoconstriction, while aldosterone promotes sodium and water retention. These actions increase blood volume and blood pressure to compensate for reduced cardiac output.
C. Decreased erythropoietin: Erythropoietin stimulates red blood cell production to improve oxygen delivery. In heart failure, erythropoietin secretion is usually increased in response to renal hypoperfusion, not decreased. Reduced erythropoietin would impair oxygen transport rather than compensate for low cardiac output.
D. Decreased catecholamines: Catecholamines (epinephrine and norepinephrine) increase heart rate and contractility to maintain cardiac output. In heart failure, sympathetic activation elevates catecholamine levels. Decreased catecholamines would reduce compensatory support and worsen cardiac output.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. Acidosis depresses respirations: While acidosis can affect the respiratory drive, it is not the primary cause of hypoxemia in pneumonia. William’s low PO2 is due to impaired gas exchange rather than depressed ventilatory effort.
B. Oxygen diffusion is impaired by the congestion: In pneumonia, alveoli fill with inflammatory exudate, mucus, and cellular debris. This fluid buildup creates a barrier to oxygen diffusion from the alveoli into the pulmonary capillaries, resulting in hypoxemia and low arterial PO2.
C. Infection reduces the effectiveness of the heart: Cardiac function may be influenced by systemic infection, but William’s hypoxemia is primarily pulmonary in origin. The heart’s pumping ability does not directly explain decreased oxygenation in the alveoli.
D. Inflammatory exudates absorb oxygen from alveolar air: Exudates do not actively consume oxygen. Instead, they physically block gas exchange by filling alveolar spaces. The impaired diffusion, rather than absorption by exudates, leads to low oxygen levels in the blood.
Correct Answer is A
Explanation
Diabetes insipidus is characterized by a deficiency of antidiuretic hormone (ADH) or a renal resistance to its effects. In central diabetes insipidus, the posterior pituitary fails to produce sufficient ADH, leading to lower-than-normal blood levels. This results in excessive urine output and risk of dehydration. Low ADH levels reduce water reabsorption in the kidneys, causing dilute urine and increased thirst as the body attempts to maintain fluid balance.
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